Silencer with inner closed hollow body



June 27, 1967 G. E. L. WALKER 3,327,809

SILENCER WITH INNER CLOSED HOLLOW BODY Filed Oct. 25, 1964 2 Sheets-Sheet 1 GaRooM EDunRnes LlNo WALKER June 27,1967 G. E. 1.. WALKER SILENCER WITH INNER CLOSED HOLLOW BODY 2 Sheets-Sheet 2 Filed Oct 25, 1964 Inventor GORDON Eowmoas Luvo WALKER maewwzw Attorney United States Patent 3 Claims. (a. 181-59 The invention relates to silencers for the exhaust gases from internal combustion engines, the silencer of the m vention being particularly suitable for use in conjunction with internal combustion engines of the piston type, although it is applicable also to other classes of internal combustion engines, such as gas turbines.

One of the objects of the invention is to construct a silencer in such manner that the corrosive effect of condensed products of combustion will be minimised.

Another object of the invention is to provide a silencer which will create only a moderate resistance to flow of the gases through it.

A further object of the invention is to provide a silencer which will act effectively in suppressing noise created by the exhaust gases as they come from the engine and are discharged to atmosphere.

The silencer of the invention comprises an outer casing having an inlet opening for admission of exhaust gases to the casing and an outlet opening for escape of the gases from the casing, and a core arranged within the casing, the core being so shaped and disposed as to leave between it and the casing an annular passageway, through which the exhaust gases flow on their way from the inlet opening to the outlet opening.

Reference is now made to the accompanying drawings which illustrate five forms of silencers embodying the invention, and in which:

FIGURE 1 is a longitudinal sectional view of the first form;

FIGURE 2 is a cross-sectional view on the lme II-II in FIGURE 1;

FIGURE 3 is a longitudinal sectional view of the second form;

FIGURE 4 is a cross-sectional view on the line IV-IV in FIGURE 3;

FIGURE 5 is a longitudinal sectional view of the third form;

FIGURE 6 is a cross-sectional View on the line VIVI in FIGURE 5;

FIGURE 7 is a longitudinal sectional view of the fourth form;

FIGURE 8 is a cross-sectional view on the line VIII VIII in FIGURE 7;

FIGURE 9 is a longitudinal sectional view of the fifth form, and

FIGURE 10 is a cross-sectional view on the line XX in FIGURE 9.

Like reference symbols are used to indicate similar parts throughout the drawings.

The construction according to FIGURES 1 and 2 consists of a horizontally extending cylindrical outer casing 1 having front and rear end closures 2 and 3 of substantially conical form, the casing and closures being made from sheet metal.

The front end closure 2 is fitted with a projecting tubular metal stub 4 providing for admission of the exhaust gases to the interior of the casing 1, this stub being adapted for connection to the usual pipe from the exhaust manifold of the engine.

3,327,809 Patented June 27, 1967 ICC The rear end closure 3 is also fitted with a projecting tubular metal stub 5 providing for escape of the gases from the casing 1. The gases may be released directly to atmosphere from the stub 5, or the latter may be adapted for connection to a tail pipe.

Within the casing 1 there is provided a horizontally extending cylindrical core generally indicated at 6. The core consists of a cylindrical shell 7 made from perforated sheet metal or metal mesh, the shell being closed at its front and rear ends by caps 8 and 9. The space within the closed shell is filled with heat-proof fibrous material 10 such as metal shavings or glass wool, the latter material being preferred as it is also corrosion proof.

The total length of the core 6 is less than that of the casing 1, while its diameter is also less than the internal diameter of the casing. The core has its axis coincident with that of the casing 1 and is arranged substantially midway betWeen the end closures 2 and 3, the core being held in this position by brackets 11 extending between the end caps 8 and 9 and the casing 1 and secured to these parts. With this arrangement, a space, indicated at 2a in FIG- URE 'l, is left between the front end closure 2 of the casing 1 and the front end cap 8 of the core 6, while a further space, indicated at 3a, is left between the rear end cap 9 of the core and the rear end closure 3 of the casing. At the same time, the shell 7 of the core 6 acts, in conjunction with the cas'ing 1, to form between the two an annular passageway 12 communicating at its ends with the two spaces 2a and 3a. Either one or each of these two spaces may be sufiiciently largeto form an expansion chamber. 7

When the hot exhaust gases enter the casing 1 through the inlet stub 4, they are received by the space 2a, the core then compelling them to travel along the annular passageway 12, from which they pass into the space 3a and thence, through the stub 5, to atmosphere. This ensures that the casing will quickly become heated and will be maintained thus while the engine is running. It has been "found by experience that, due to such rapid warm-up, condensation will be minimized, and corrosion caused by the products of combustion reduced to a marked extent. Afurther advantage resulting from the. provision of an annular passageway 12 is that, as the latter is practically free from obstruction, the exhaust gases will have an easy passage through the silencer with a consequent notable reduction of undesirable back pressure.

When the engine has been running for some time, the core itself willbecome hot and as it is not exposed to ex terior cooling, it will act as a heat conserver. Hence, the silencer will remain warm for a comparatively long time after-the engine 'has been stopped, the result being that rapid warm-up will be even further there having-been an is started up again.

As the shell 7 of the core'6 is perforated and the core is filled with fibrous material, the core will act as a good sound absonbing device, the exhaust gases issuing from the outlet stub 5 thus being effectively silenced.

The construction illustrated in FIGURES 3 and 4 has numerous features in common with that according to FIGURES 1 and 2. i

In the present instance, the front end cap 8 of the core 6 is formed with a centrally disposed cylindrical recess 13 which penetrates part-way into the core and has a closed inner end 14.

The internal diameter of the recess 13 is greater than the external diameter of the inlet stub 4 and this latter is arranged in axial alignment with the casing 1. The stub 4 is formed with an extension 4a which passes rearwardly promoted in spite of through the closure 2 and projects part-way into the recess 13, the extension 4a being reinforced by stays 15 extending between it and the recess 13.

With the arrangement just described, the recess 13 acts to suppress noise from the exhaust gases as they issue from the inner end of the extension 4a of the stub 4 and then pass forwardly along the recess on their way to the annular passageway 12 and thence to the outlet stub 5. The hot exhaust gases passing along the recess also act to impart heat to the core 6.

The inner end portion of the extension 4a of the stub 4 may be perforated as indicated at 16 so that the closed inner end 14 of the recess 13 will not act to unduly obstruct the free flow of exhaust gases from the extension 4a into the recess.

The construction according to FIGURES 5 and 6 may be regarded as an alternative to the construction just previously described.

Here, the inlet stub 4 is without the inward extension 4a shown in FIGURES 3 and 4, but a chamber 13a is provided within the core 6, the chamber extending partway along the core from the front end cap 8 thereof. The inner end of the chamber 13a is closed as indicated at 14, while the end cap is formed in such manner as to either leave the forward end of the chamber fully open to the space 2a or, as shown, to provide a smaller opening 8w leading into the chamber from that space.

With the arrangement just described, a part of the exhaust gases passing into the space 2a from the stub 4, enter the chamber 13a through the fully open end thereof, or through the restricted opening 8a, the chamber then acting as an acoustic absorber which may be tuned to a particular range of sound frequencies.

In other respects the construction according to FIG- URES 5 and 6 is substantially the same as that shown in FIGURES 3 and 4.

FIGURES 7 and 8 illustrate a construction in which the exhaust gases are caused to flow, in two passes, through the core 6, as well as by a third pass through the annular passageway 12, from the inlet stub 4 to the outlet stub 5.

Here the core 6, constituted by the shell 7 and end caps 8 and 9, is made wholly of sheet metal so that it forms a closed body which is simply left hollow, while the stubs 4 and 5 are radially off-set from each other.

The inlet stub 4 has a rearward extension 4b which passes through the front end closure 2 of the casing 1 and then right through the core 6 from one end thereof to the other.

The outlet stub 5 has a forward extension 5a passing through the rear end closure 3 of the casing 1 and then right through the core 6 from one end thereof to the other.

With this arrangement, and as indicated by the arrows in FIGURE '7, the exhaust gases from the engine flow through the inlet stub 4 and then through its extension 4b until they reach the space lying between the rear end plate 9 of the core and the closure 3 at the rear of the casing 1. From this space, the gases flow forwardly along the annular passageway 12, then finding their way into the open forward end of the extension 5a of the outlet stub 5, the gases then flowing rearwardly along these latter parts to the discharge point.

As shown in FIGURE 7, the core 6 may be formed with two partitions 17 spaced inwardly from the end caps 8 and 9 to thereby provide boxes 18 at the ends of the core. These boxes may be fully closed or, as shown, the end caps 8 and 9 may be formed with openings 8b and 9a, respectively, leading into the boxes so that the boxes can be tuned as resonators to reduce particular sound frequencies.

The construction according to FIGURES 7 and 8 may be modified by making the part of the shell 7 of the core lying between the partitions 17, of perforated sheet metal or metal mesh, in which case the space enclosed by this part of the shell and the partitions may be filled with heatproof fibrous material as in the other constructions described.

The arrangement described with reference to FIG- URES 7 and 8 is particularly suited to constructions in which, as illustrated, the end closures 2 and 3 of the casing 1 are flat instead of being conical.

The construction according to FIGURES 9 and 10 is similar to that of FIGURES 1 and 2. Here, the end caps 8 and 9 of the core 6 are formed with side walls and 9b so that they are shaped as cups the open mouths of which face, but are spaced inwardly of, the inner ends of the stubs 4 and 5 respectively, the cups thus opening into the spaces 2a and 3a.

With this arrangement, the cup-like end caps 8, 8c and 9, 9b not only act in conjunction with the spaces 2a and 3a as expansion chambers, but also serve as resonance chambers. e

In carrying the invention into practical effect, good results will be obtained when the cross-sectional area of the annular passageway 12 between the casing 1 and the core 6 is equal to or not more than twice the cross-sectional area of the opening provided for admission of the exhaust gases to the casing.

While in the various embodiments described and illustrated, the exhaust gases flow through the silencer in a direction generally from left to right, it becomes possible to so connect up the silencer that the flow will be in the reverse direction while still giving good results.

While, generally speaking, the silencer will be so installed that its axis extends horizontally, it will work satisfactorily if arranged at other attitudes, such as vertically or at an angle lying between the horizontal and the vertical.

In the description with reference to the drawings, the casing 1 and core 6 are stated to be cylindrical, thus being of circular cross-section, and this is how they are depicted in the drawings. This, however, has been done merely for simplicity of description and illustration, and I wish it to be understood that the parts in question may have other cross-sectional shapes, elliptical for example, so long as the annular passageway 12 is present, and I desire that the appended claims shall, where applicable, be read with that fact in mind.

What I claim and desire to secure by Letters Patent of the United States of America is:

1. A silencer for the exhaust gases from internal combustion engines, comprising an outer casing having an inlet opening for admission of exhaust gases to the casing and an outlet opening for escape of the exhaust gases from the casing, and a core arranged within the casing and having an imperforate lateral wall, the core being so shaped and disposed as to leave between its lateral wall and the casing an annular passageway, and the outlet and inlet openings being so arranged that the exhaust gases are constrained to flow through the entire length of said annular passageway on their way from the inlet opening to the outlet opening, said casing being cylindrical and having enclosures, one of the enclosures being fitted with an outwardly projecting tubular stub providing the inlet opening, and the other enclosure being fitted with an outwardly projecting tubular stub providing the outlet opening, the core comprising a cylindrical shell of sheet metal closed at its ends by caps so that it is in the form of a closed hollow body, and wherein in the inlet and outlet stubs of the casing are radially off-set from each other and the inlet stub is formed with an extension which passes through the closure at the corresponding end of the casing and then through the core from one end thereof to the other, while the outlet stub is formed with an extension passing through the closure at the other end of the casing and then through the core from one end thereof to the other. e

2. A silencer in accordance with claim 1 and wherein the core is formed with two partitions spaced inwardly of the end caps to thereby form boxes at the ends of the Core- 3. A silencer in accordance with claim 2 and wherein the end caps are formed with openings leading into the boxes.

References Cited UNITED STATES PATENTS 2,043,030 6/1936 Bourne. 2,056,608 10/ 1936 Jack. 3,114,431 12/1963 Sanders 18150 3,243,010 3/1966 Flynn 181-53 XR FOREIGN PATENTS 9,297 1907 Great Britain. 1,226,438 2/ 1960 France.

RICHARD B. WILKINSON, Primary Examiner. R. S. WARD, Assistant Examiner. 

1. A SILENCER OF THE EXHAUST GASES FROM INTERNAL COMBUSTION ENGINES, COMPRISING AN OUTER CASING HAVING AN INLET OPENING FOR ADMISSION OF EXHAUST GASES TO THE CASING AND AN OUTLET OPENING FOR ESCAPE OF THE EXHAUST GASES FROM THE CASING, AND A CORE ARRANGED WITHIN THE CASING AND HAVING AN IMPERFORATE LATERAL WALL, THE CORE BEING SO SHAPED AND DISPOSED AS TO LEAVE BETWEEN ITS LATERAL WALL AND THE CASING AND ANNULAR PASSAGEWAY, AND THE OUTLET AND INLET OPENINGS BEING SO ARRANGED THAT THE EXHAUST GASES ARE CONSTRAINED TO FLOW THROUGH THE ENTIRE LENGTH OF SAID ANNULAR PASSAGEWAY ON THEIR WAY FROM THE INLET OPENING TO THE OUTLET OPENING, SAID CASING BEING CYLINDRICAL AND HAVING ENCLOSURES, ONE OF THE ENCLOSURES BEING FITTED WITH AN OUTWARDLY PROJECTING TUBULAR STUB PROVIDING THE INLET OPENING, AND THE OTHER ENCLOSURE BEING FITTED WITH AN OUTWARDLY PROJECTING TUBULAR STUB PROVIDING THE OUTLET OPENING, THE CORE COMPRISING A CYLINDRICAL SHELL OF SHEET METAL CLOSED AT ITS ENDS BY CAPS SO THAT IT IS IN THE FORM OF A CLOSED HOLLOW BODY, AND WHEREIN IN THE INLET AND OUTLET STUBS OF THE CASING ARE RADIALLY OF-SET FROM EACH OTHER AND THE INLET STUB IS FORMED WITH AN EXTENSION WHICH PASSES THROUGH THE CLOSURE AT THE CORRESPONDING END OF THE CASING AND THEN THROUGH THE CORE FROM ONE END THEREOF TO THE OTHER, WHILE THE OUTLET STUB IS FORMED WITH AN EXTENSION PASSING THROUGH THE CLOSURE AT THE OTHER END OF THE CASING AND THEN THROUGH THE CORE FROM ONE END THEREOF TO THE OTHER. 